and wait until you hear what senator john mccain said about waterboarding and john kerry. good morning, i'm mara schiavocampo. a bitterly cold arctic blast is gripping half the nation this morning. exposure is suspected in at least four deaths, dangerously low temperatures is shutting down schools and causing water main breaks. on tuesday, one person was killed in this massive pile up of 20 vehicles caused by icy conditions in michigan. nbc meteorologist bill karins has more on this dangerous cold snap. where is it headed? >> it's settled in, just sitting there now. for many of us, especially on the eastern seaboard, this is the coldest morning in a couple years, especially when you factor in the windchills. here's the set up. it's not everyone. we're very mild today, great lakes, oklahoma, texas, through the gulf states, if you're on the other side of the jet stream from the northern plains, the great lakes and northeast, it's just like yesterday if not worse. the windchills this morning, right now the worst of it is in northern new england. this is just the temperatures